Designer injects bogus "<normaloff>.</normaloff>." for icon properties

Editing an existing UI file with Designer and saving the file results in icon properties which before only had an iconset element with a theme attribute set to suddenly have some bogus "normaloff>.</normaloff>." content inserted:

  <widget class="QPushButton" name="pushButton">
   <property name="icon">
    <iconset theme="dialog-ok"/>
   </property>
  </widget>

becomes

  <widget class="QPushButton" name="pushButton">
   <property name="icon">
    <iconset theme="dialog-ok">
     <normaloff>.</normaloff>.</iconset>
   </property>
  </widget>

Which results in some bogus code generated from uic:

    QIcon icon;
    QString iconThemeName = QString::fromUtf8("dialog-ok");
    if (QIcon::hasThemeIcon(iconThemeName)) {
        icon = QIcon::fromTheme(iconThemeName);
    } else {
        icon.addFile(QString::fromUtf8("."), QSize(), QIcon::Normal, QIcon::Off);
    }

How to reproduce

1. Start Designer, create a new empty dialog
2. Add a push button
3. Edit the icon and select a theme name, "dialog-ok"
4. Save the file as "test.ui" and exit Designer
5. Check the file content in a text editor
6. Start Designer again and load "test.ui"
7. Move the button a bit
8. Save the file again
9. Check the file content in a text editor